#Placing footing per frost depth how to#
#Placing footing per frost depth install#

Grade beam with brick veneer/ exterior and under slab insulationįigure 4-1.Concrete wall with brick veneer/ under slab insulation.However, installing the structural supports at a point at least 2 feet below the maximum frost depth provides an anchor to help prevent the structure from being forced up and out of position. The result is a chaotic movement of hardened earth that has enough force to bend posts, break rock, and shift entire building foundations.Įven after the frost lens melts, allowing the dirt to settle back into position, the structure will likely remain unbalanced and damaged. This lens pushes dirt, rocks, and any other objects upwards, as it gradually expands. A frost heave occurs when the water in the soil freezes and expands, forming a pocket of ice called a frost lens. When posts, foundations, footings, and other supports are installed above the frost line, the structures become vulnerable to significant damage that can be caused by frost heaves. Frost heave can damage foundations, footings, and other important structural elements. Alternately, there are many frost line depth maps that display that average frost line maximum for the region. Just keep in mind that this map only indicates the current frost depth, so if it’s checked in the middle of summer then most locations will not have any frost.

#Placing footing per frost depth install#

With this variability in mind, it’s necessary to check local building codes, as well as frost line depth maps to get an accurate idea of how deep you will need to dig in order to install deck footings, fence posts, and foundations.įor accurate, up-to-date information about the current frost level in your area, the National Weather Service provides a country-wide frost line depths map that can be referenced by entering your address or zip code. The weather across the United States doesn’t remain consistent, so it only makes sense that the colder areas of the country would have a different frost line depth than the warmer areas of the country. Frost line depths vary greatly across the United States. Always refer to local building codes to find out the approved depth to install footings. Testers put a bag of water with measurement indicators into the tube and determine the depth based on the line at which the water freezes. Testing the exact depth relies on instruments known as frost tubes that consist of a small hollow tube that is inserted into a drilled hole in the frozen ground. The ground contains moisture that is used by plants and animals to live and thrive, however, when cold weather hits, the groundwater begins to freeze and expand, pushing and crushing objects that are in the frozen dirt.įrost lines are typically determined by the moisture and soil content, as well as the average temperatures in the region.

#Placing footing per frost depth how to#

It’s necessary to understand what the frost line is and how to determine frost line depth in order to grasp the risks associated with constructing buildings or other structures. Frost line is the depth at which groundwater freezes. Related: The Dos and Don’ts of Setting a Fence Post 1.

Taking this time to plan will help make sure that you have the right amount of material and that the footings can be securely installed in the ground below the frost line. It’s important to find out the exact required frost line depth from your local building codes before planning a project. Soil content, moisture content, and average temperatures throughout the year all affect the frost line. While the concept of frost line is universal, the actual frost line depth changes depending on the location. Another important part of building anything on a foundation is understanding frost line depths in order to ensure that the structure lasts for years to come, and doesn’t succumb to the structural damage that can be caused by frost heave.

Installing a fence, deck, permanent gazebo, or a new workshop requires knowledge of permits and building codes.